The Mine Health and Safety Act states that “the installation of incline conveyor belts must include the fitting and use of one or more devices to prevent run-back or run-on, to prevent injury by materials or minerals falling from a conveyor belt”, says engineering solutions provider BMG business unit manager Carlo Beukes.
He states that the BMG team works closely with engineers in the coal sector to maintain critical safety standards and ensure adherence to current legislation. Stringent measures are taken to prevent roll back incidents that can cause injuries during conveying operations.
The Tsubaki backstop cam clutches, which prevent reverse rotation of drive shafts, offer a simple and cost-effective means to protect capital equipment and enhance safety on site. This range is available with different capacities and designs, to provide optimal functional characteristics for three basic modes of operation: over-running, indexing and backstopping.
“Our technical experts advise mines on the selection of the correct cam clutch for each application and appropriate installation and use, for optimum performance and safety at every mine.”
BMG’s range of Tsubaki backstop cam clutches, which is suitable for high- or low-speed applications, meets the requirements of current mining legislation and has many critical features not found in conventional models.
The high-torque, high-speed Tsubaki BS-F series – designed for high-speed inclined and long overland belt conveyors and bucket elevators – is particularly well suited for coal mining applications. The narrow width I-beam torque arm is a drop-in replacement to conventional anti-rollback devices, which allows for quick and easy on-site installation. This design also enables the replacement of an old backstop with the new BS-F design, without the need for modification to the existing layout.
Although this series has a narrower width than other models, the downsized unit exceeds the requirements of high-speed inclined belt conveyors, with the benefits of space-saving and reduced installation time.
A common cause of conventional backstop failure is oil leakage. Tsubaki has eliminated this risk in the BS-F series by designing the backstop to operate with grease and a specially-designed labyrinth seal. The absence of an oil level gauge creates a more reliable safety device.
Other important features of this series include a nonroll over cam and roller design, which offers higher backstop torque capacities and lower running temperatures than conventional anti-rollback devices. Further, a flexible labyrinth seal mechanism prevents the ingress of dust and water in abrasive conditions and a double-lip oil seal and multitemperature grease enable safe operation at a wide ambient temperature range – from –40 °C to 65 °C.
The cam and roller cage orbit at low speed, continually conveying grease internally from the bottom to the top of the mechanism. The constant circulation of grease minimises internal friction and reduces operating temperature for dependable operation. Maintenance intervals are between 7 500 hours and 8 000 hours and the effective service life of the units is also significantly extended, compared with conventional oil-filled units.
For extended service life, correct lubrication methods and dust prevention care are critical. BMG recommends the use of a maintenance kit and Tsubaki-approved EP-free grease for easy and effective maintenance of the BSF series. The company offers customers a complimentary Tsubaki maintenance kit with BSF backstops larger than a 200 mm shaft, which allows for easy servicing of the unit during operation, without the need to remove the shaft.
BMG also supplies a range of customised Tsubaki reclaimer chains, designed and manufactured with various options, to suit specific requirements of reclaimers used in the coal mining sector.
“Reclaimer chains should provide the longest service life to achieve the best overall value. Chain must have large bearing areas, high hardness and deep case depth, to provide optimum performance,” says BMG Tsubaki product specialist Gavin Kirstein.
Kirstein notes that Tsubaki engineers have implemented these principles while retrofitting many reclaiming conveyors with chain and sprockets, achieving longer service life than original-equipment manufacturers’ chains. “Owing to their complex requirements, reclaimer chains are manufactured on a made-to-order basis and are designed and manufactured to meet the specific, unique requirements of each site.”
Tsubaki has developed new reclaimer chains with outboard rollers that prevent the build-up of abrasive particles between bushes and rollers, solving the problem of premature wear. A new labyrinth construction, with improved antidust capabilities, prevents debris from infiltrating the outboard rollers and chain wear areas. In addition, the outboard rollers are sealed for life and require no additional maintenance.
Tsubaki’s customisable large size conveyor chains are also available from BMG, with a selection of base materials, corrosion-resistant coatings, attachments and rollers.
BMG’s technical team conducts full plant surveys and advises on the selection of the correct cam clutch and reclaimer chain for each application, as well as the appropriate installation and usage, to ensure optimum perormance and improved safety standards.
BMG’s cam clutches are also used for belt conveyors for materials handling; metals, timber, pulp and wood chip applications; as well as for bucket elevators for cement and grain. These units are also installed to enhance performance of large drift conveyors and screw pumps.
BMG stocks a variety of the Tsubaki backstops locally and test runs every unit before delivery. The complete range of Tsubaki power transmission components is available from BMG’s national branch network, which offers a technical advisory and 24-hour backup service.